package com.yami.shop.security.api.util;

import cn.hutool.core.codec.Base64;
import cn.hutool.http.HttpUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.AlgorithmParameters;
import java.security.Security;
import java.util.Arrays;
import java.util.HashMap;

/**
 * <p>
 * TODO
 * </p>
 *
 * @author laoxie
 * @date 2023/4/11 19:40
 */
public class WeChatUtil {
    public final static String jsCode2SessionUrl = "https://api.weixin.qq.com/sns/jscode2session";

    /**
     * 获取SessionKey
     * @param appid
     * @param secret
     * @param code
     * @return
     */
    public static JSONObject getSessionKeyOrOpenId(String appid, String secret, String code) {
        HashMap<String, Object> requestUrlParam = new HashMap<>();
        //小程序appId
        requestUrlParam.put("appid", appid);
        //小程序secret
        requestUrlParam.put("secret", secret);
        //小程序端返回的code
        requestUrlParam.put("js_code", code);
        //默认参数
        requestUrlParam.put("grant_type", "authorization_code");
        //发送post请求读取调用微信接口获取openid用户唯一标识
        String result = HttpUtil.get(jsCode2SessionUrl, requestUrlParam);
        JSONObject jsonObject = JSONUtil.parseObj(result);
        return jsonObject;
    }

    /**
     * 获取用户信息
     * @param encryptedData
     * @param sessionKey
     * @param iv
     * @return
     */
    public static JSONObject getUserInfo(String encryptedData, String sessionKey, String iv) throws Exception {
        // 被加密的数据
        byte[] dataByte = Base64.decode(encryptedData);
        // 加密秘钥
        byte[] keyByte = Base64.decode(sessionKey);
        // 偏移量
        byte[] ivByte = Base64.decode(iv);
        // 如果密钥不足16位，那么就补足.  这个if 中的内容很重要
        int base = 16;
        if (keyByte.length % base != 0) {
            int groups = keyByte.length / base + (keyByte.length % base != 0 ? 1 : 0);
            byte[] temp = new byte[groups * base];
            Arrays.fill(temp, (byte) 0);
            System.arraycopy(keyByte, 0, temp, 0, keyByte.length);
            keyByte = temp;
        }
        // 初始化
        Security.addProvider(new BouncyCastleProvider());
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding", "BC");
        SecretKeySpec spec = new SecretKeySpec(keyByte, "AES");
        AlgorithmParameters parameters = AlgorithmParameters.getInstance("AES");
        parameters.init(new IvParameterSpec(ivByte));
        // 初始化
        cipher.init(Cipher.DECRYPT_MODE, spec, parameters);
        byte[] resultByte = cipher.doFinal(dataByte);
        if (null != resultByte && resultByte.length > 0) {
            String result = new String(resultByte, "UTF-8");
            return JSONUtil.parseObj(result);
        }
        return null;
    }
}
